Memory disk accessing apparatus

• US 4,972,364 A
• Filed: 04/24/1989
• Issued: 11/20/1990
• Est. Priority Date: 02/13/1987
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Barrett, Gerald G., Shaheen-Gouda, Amal A., Pasha, Syed Z.
• Primary Examiner(s): Fleming, Michael R.
• Assistant Examiner(s): CHUN, DEBRA
• Application Number:
  US07/342,727
• Time in Patent Office: 575 Days
• Field of Search: 364/200 MS File, 364/900 MS File, 365/241
• US Class Current: 711/117
• CPC Class Codes: G06F 12/0862 with prefetch
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2212/6026 Prefetching based on access pattern detection, e.g. stride based prefetch
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0673 Single storage device

Abstract

A data processing system including at least one storage device for storing and retrieving data from several rotating tracks where each track includes sequentially located blocks for the storage of data. A storage interface is connected for controlling this storage device. The storage interface includes a data buffer for storing data retrieved from the storage device. A storage driver is provided that receives storage access commands from a processor and provides commands to the interface in response to these commands from the processor. This storage driver further includes the capability to provide commands for requesting data that has not been requested by the processor. This data not requested by the processor is stored in a data buffer. These commnads for data not requested by the processor are issued in accordance to procedure that computes these commands called read ahead commands based on the order of commands received from the processor and also based on the number of storage devices in use.

Claims

1. A data processing system comprising:

at least one storage means, each for storing and retrieving data from a plurality of rotating tracks and each including sequentially located sectors for the storage of data;

means, connected to each of said storage means, for identifying data stored on each of said sectors of said plurality of rotating tracks;

a storage interface means for controlling the storing and retrieving of data from one of said storage means and including a data buffer means for storing data retrieved from or to be stored in said storage means; and

a processor including an application program and a storage driver means for receiving a plurality of access requests from said application program and for providing first access commands to said storage interface means in response thereto and including means, connected to said identifying means and said storage driver means, for determining when at least tow of said access requests in said storage driver means are for data that, according to said identifying means, are stored in sequentially located sectors on one of said rotating tracks, and means for providing second access commands for data not requested by said application program in response to such determination.

2. A data processing system according to claim 1 wherein said means for providing second access commands for data not requested by the application program, includes means for storing said data not requested by said application program in said data buffer means.

3. A data processing system according to claim 2 wherein said storage driver means for providing said second access commands for data not requested by the application program includes means for providing such access commands in response to said access requests for requested data.

4. A data processing system according to claim 3 wherein said storage driver means includes means for determining when access requests from said application program include access requests for data stored in the data buffer means and in response thereto, for providing said second access commands for retrieving data from said data buffer means.

5. A data processing system according to claim 4 wherein said storage driver means includes means for determining from said access requests from said application program if data is being requested from said storage means that is sequentially located in one of the plurality of tracks and in response thereto, for issuing said second access commands for accessing data contained in a plurality of sequentially located sectors for storage in said data buffer means.

6. A data processing system comprising:

at least one storage means, each for storing and retrieving data from a plurality of rotating tracks and each including sequentially located sectors for the storage of data;

means, connected to each of said storage means, for identifying data stored on each of said sectors of said plurality of rotating tracks;

a storage interface means for controlling the storing and retrieving of data from one of said storage means and including a data buffer means for storing data retrieved from said storage means and a plurality of command buffers each for storing access commands for a respective one of said storage means and said data buffer means; and

a processor including an application program and a storage driver means for receiving access requests from said application program, storing said received access requests in one of a plurality of command queues, providing first access commands in response thereto to one of a plurality of said command queues, including means, connected to said identifying mean sand said plurality of command queues, for determining when at least tow of said access requests in said command queues are for data that, according to said identifying means, are stored in sequentially located sectors on one of said rotating tracks, and including means for providing second access commands for data not requested by said application program in response to a determination that sequentially located data is being requested by said access requests.

7. A data processing system according to claim 6 wherein said means for providing said second access commands for data not requested by the application program, includes means for storing said data not requested by said application program in said data buffer means.

8. A data processing system according to claim 7 wherein said storage driver means for providing second access commands for data not requested by the application program includes means for providing such second access commands in response to said access requests from said application program.

9. A data processing system according to claim 8 wherein said storage driver means includes means for determining when access requests from said application program include requests for data stored in the data buffer means and in response thereto for providing said second access commands for retrieving data from said data buffer means.

10. A data processing system according to claim 9 wherein said storage driver means includes means for determining if access requests int he command queues or said command buffers include said first access commands to retrieve sequential data sectors in said storage means tracks and in response thereto providing said second access commands for data not requested by application program.

11. A data processing system according to claim 10 wherein said storage driver means includes means for providing said first access commands from said command queues to said command buffers for the respective storage means.

12. A data processing system according to claim 11 wherein said storage driver means includes means for providing said second access commands for data not requested by said application program to said command buffers.

13. A data processing system according to claim 12 wherein said storage interface means includes means for indicating to said storage driver means when either a first or second access command in one of said command buffers has been completed.

14. A data processing system according to claim 13 wherein said second access commands for data not requested by said application program are provided in response to a determination of an active number of storage means.

15. A data processing system according to claim 14 wherein each of said second access commands for data not requested by said application program are for an amount of data equal to an amount from a previous first access command for data requested by said application program.

16. A data processing system according to claim 15 wherein said storage driver means includes means for sequentially ordering said access requests from the application program int he command queues according to an access procedure for providing access of data form each of said storage means.

17. A data processing method comprising the steps of:

storing and retrieving data from a plurality of rotating tracks, each including sequentially located sectors for the storage of data;

identifying data stored on each of said sectors of said plurality of rotating tracks;

controlling the storing and retrieving of data from one of said rotating tracks with a storage interface means and storing data retrieved from or to be stored in a data buffer in said storage interface means; and

receiving a plurality of access requests form an application program and providing first access commands to said storage interface means in response thereto and determining when at least two of said access requests in said storage driver means are for data that are stored in sequentially located sectors on one of said rotating tracks and providing second access commands for data not requested by said application program in response to such determination.

18. A data processing method comprising the steps of:

storing and retrieving data from a plurality of rotating tracks, each including sequentially located sectors for the storage of data;

identifying data stored on each of said sectors of said plurality of rotating tracks;

controlling the storing and retrieving of data from one of said rotating tracks in a storage means and storing data retrieved from said rotating tracks in a data buffer; and

receiving access requests from an application program, storing said received access requests in one of a plurality of command queues, providing first access commands in response thereto to one of a plurality of said command queues, determining when at least tow of said access requests in said command queues are for data that are stored in sequentially located sectors on one of said rotating tracks, and providing second access commands for data not requested by said application program in response to a determination that sequentially located data is being requested by said access requests.